Multiple part oil-control ring for piston

Details Multiple part oil-control ring for piston Multiple part oil-control ring for piston

1987-01-12

1988-07-26

Garrett, Robert E.

Expansible chamber devices

Piston

Radially adjustable side wall portion

92172, 92192, 92257, 277216, F16J 106

Patent

active

047592664

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a multiple-part oil control ring for a piston e.g. in an internal combustion engine, or a compressor.
A known construction of a ring of this type comprises an expander or spring ring and one or more lamellar rings or rails supported by the expander.
The composite ring is located in a groove in the piston and the expander is arranged to urge the rails both radially outwards against the cylinder wall and axially against the walls of the groove.
The expander may take many forms though one form frequently encountered comprises a ring formed by folding a flat strip with a series of alternate cut-outs along each edge to form a U-shaped channel section and subsequently bending the channel section into a generally U-sectioned ring.
In the motor industry, engine designers wish to reduce engine dimensions to improve car body profiles and to reduce engine weight. One way of achieving this is to reduce the engine block dimension in the direction of the engine cylinders, however, it is generally preferable to do so without affecting the cylinder capacity and compression parameters. This can be done by reducing the height of the piston, and indeed this is frequently an objective sought by piston designers.
One of the drawbacks of the folded-strip form of expander described above resides in the fact that its minimum axial thickness, in practice, tends to be quite large if it is to perform its spring/support function effectively.


SUMMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an oil control ring having a comparatively small dimension in the axial direction of the piston, in order to reduce the piston height.
According to the invention, there is provided a multiple-part oil-control ring for a piston which comprises an expander ring and at least one lamellar rail supported by the expander, the expander being formed from a flat strip of spring material having a first series of notches along one edge and a second series of notches alternating with the first series along the other edge, the material between the notches of the first series and the other edge of the strip being deformed to provide lugs standing proud of the surface of the strip, the strip being bent to form the expander ring with the one edge at the outer circumference of the ring and the other edge at the inner circumference of the ring, whereby the lugs provide a series of supports for the lamellar rail.
The fact that the expander ring is not folded in the axial sense means that its axial thickness may be less than that of a comparable expander of the known type described above.
Preferably, the control ring includes two rails, one on either side of the expander ring, in which case the lugs should protrude on both sides of the expander ring to support the two rails. Preferably, the lugs are punched from the strip material to protrude alternately from each surface of the expander ring.
Preferably, there are protrusions from the surface of the expander ring between the notches of the second series and the outer circumference, which act to space an annular rail from the expander ring surface. These protrusions preferably extend from both surfaces of the expander ring to space one annular rail from each surface of the expander ring and may be punched from the strip material to protrude alternately from each surface of the expander ring, to space an annular rail from each surface of the expander ring.
These protrusions, in spacing the rails from the expander ring, improve drainage from between the rails to the piston groove, which might otherwise be reliant upon the second series of notches.
Alternatively, there may be only one rail associated with the expander ring, this rail preferably being on the top or piston crown side of the expander ring. In such a construction, the lugs and protrusions on the expander ring preferably extend on one side only of the expander ring.
In a preferred embodiment the notches may be shaped to have neck widening to an opening exte

REFERENCES:
patent: 2817765 (1957-12-01), Heiss
patent: 2904377 (1959-09-01), Endres et al.
patent: 3627333 (1971-12-01), Hill
patent: 3738668 (1973-06-01), Minegishi
patent: 3768818 (1973-10-01), Minegishi

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